The present invention relates to a drum of disposable type to carry a coil of a continuous flexible object including cable, line, wire cable, rope, ribbon, hosing, chain or the like.
It is known to use disposable drums with a size of 400 mm, this dimension referring to the diameter of the end pieces. However, the connection between the end pieces and the core in these disposable drums is not strong enough to be used for larger sizes, e.g. 500 mm and 600 mm. Wooden drums of conventional type are therefore still used for these sizes. However, the design of such wooden drums is such that they fetch a high price and must therefore be re-used in order to achieve better economy in handling cable and line. However, the return system operates extremely unsatisfactorily, thereby unfavourably affecting the economy of handling cable and line. Another drawback is that the end pieces of the wooden drum, which are nailed together out of planks, are easily damaged. Damaged wood in the drum may easily damage the cable or line itself when it is uncoiled from the rotating wooden drum, particularly if it runs off the coil in a direction not perpendicular to the axis of rotation of the drum. The damage may be so serious that the entire coil of cable or line, or parts of it, must be rejected. This also results in operating disturbance, i.e. the work in laying cable or line in the field is delayed. Another problem with wooden drums is that their centre of rotation does not usually coincide with that of the sleeve, and therefore not with the central axis of the sleeve. This is extremely unsatisfactory and absolutely unacceptable in the case of opto-cable, for instance, which is very sensitive and easily damaged due to this eccentricity during coiling and uncoiling. Deformations caused by the nature of the wood (not dead material) and errors and complications in the manufacture of the wooden drums contribute to this eccentricity. One suggestion for reducing this problem has been to replace the core of the wooden drum, made of planks, with a sleeve of iron. However, this does not solve all problems and at the same time creates new ones, such as increased weight and cost.